Spray and negative pressure cooling system



R. L.. JONES ET SPRAY AND NEGATIVE PRESSURE COOLING SYSTEM Oct. 1, 19684 Sheets-Sheet 1 Filed Dec. 20, 1965 Yea INVENTOR,

Oct. 1, 1968 R. L. JONES ET AL 3,403,726

Filed Dec. 20, 1965 4 Sheets-Sheet. 2

AJNVEN'TOR.

Oct. 1, 1968 R. L. JONES ET AL 3,403,726

SPRAY AND NEGATIVE PRESSURE COOLING SYSTEM Filed Dec 20, 1965 4Sheets-Sheet 5 29 INVENTOR.

Oct. 1, 1968 R. L. JONES ET AL 3,403,726

SPRAY AND NEGATIVE PRESSURE COOLING SYSTEM Filed Dec. 20, 1965 4Sheets-Sheet 4 INVENTOR. 40am .2

United States Patent ABSTRACT OF THE DISCLOSURE In the annealing ofsteel coils, for example, where the annealing temperature is supplied toan annealing chamber by delivering hot gases thereto, the presentinvention provides for the cooling of such gases after they have heatedthe coils. This greatly increases the capacity of the annealingapparatus, as otherwise it would take an excessive amount of time tolower the temperature of the coils below the critical range, after whichthey can be exposed to the atmosphere. Variousproblems such as the useof inert gases to avoid coloration of the coiled steel strip requirethat the same gas used for supplying the heat is also employed forlowering the temperature, and in accordance with the present invention,a cooling system is provided for rapidly cooling the gases that arewithdrawn from the annealing apparatus and return the gases to theannealing chamber in which the coils are stacked.

A feature of the invention is a pressure diflerential between the gasesflowing into the cooling chamber and the coolant surrounding the flowtubes of the gases so that it would be impossible to contaminate thegases by the coolant flowing into the tube.

The invention relates to new and useful improvements in cooling systemsfor gases by the use of sprays and negative pressure, and it isparticularly useful where the fluid to be cooled flows through a tubularenclosure which is encased at least partially by a coolant tube open tothe atmosphere at one end. A coolant such as water is sprayed into theannulus between the flow tube and coolant tube and air saturated withthe coolant is exhausted at the end opposite the end that is open to theatmosphere.

The invention will become more apparent from a consideration of theaccompanying drawings constituting a part hereof in which like referencecharacters designate like parts and in which:

FIGURES 1 and 2 are side and front elevational views, respectively, of acooling and circulating system embodying the principles of thisinvention;

FIGURE 3 is an isometric view of a modified form of the apparatus shownin FIGURES l and 2.

FIGURE 4 is a cross section taken along the line 4-4 of FIGURE 1;

FIGURE 5 is a side elevational view, partially in section, of one of thecirculating and cooling tubes of FIGURE 3;

FIGURE 6 is a cross section taken along the line 66 of FIGURE 5;

FIGURE 7 is a cross section through one of the spray heads and a portionof the tube taken along the line 77 of FIGURE 6; and,

FIGURE 8 is a vertical cross-sectional view, partially in elevation, ofa coil annealing apparatus embodying the principles of this invention.

With reference to FIGURES 1 and 2 of the drawing, the apparatus consistsof a housing 1 having a header chamber 2 connected to an inlet 3 andhaving a chamber 4 connected to an outlet 5. A partition 6 supports aplurality of tubes 7 open at the end in communication with the ICCchamber 2, the tubes extending downwardly substantially the length ofthe housing. A plurality of tubes 8 are suspended from a partition 9 andprovide an annular space around the inner tube 7, the tubes 8 beingclosed at the bottom, as shown at 13, FIGURE 1, to cause circulation ofgases from the chamber 2 through tube 7, then around the annular spaceand out into the header chamber 4, as shown by the arrows in FIGURE1..Coolant tube 10 having a bell-shaped end 11 is open to the atmosphereat 1.2 and extends the length of the tubes 7 and 8, and beyond to restupon and be supported by a partition .14 that forms a chamber with abottom plate 15 having an outlet 16 for the flow of the coolant. Aplurality of spray pipes and nozzles are connected to a supply line 17,the spray line and nozzles being generally designated by the numeral 18.

In the modification shown in FIGURE 3 of the drawing, the tubes are inan inclined instead of a vertical position, but otherwise function thesame as the apparatus shown in FIGURES 1 and 2. As shown, a header box20 is connected to a conduit 21 through which hot gases from a supplyline 22 are conducted by a fan or blower 23. A second manifold 24 isconnected to a conduit 25 which delivers the cooled gases to a point ofuse. The numeral 26 designates the outlet for a manifold chamber 27 witha fan 28 exhausting the chamber 27 to the atmosphere. An excess waterdrain 29 is provided with a water seal 30.

The spray apparatus for supplying the coolant to the fluid tube in whichthe hot gas tubes are enclosed is shown in FIGURES 5 to 7, respectively,In FIGURE 6 the outer or coolant tube 10 is spaced from tube 8 thatencases the inner tube 7 through which the gases flow under pressure andfrom which they pass through the annular chamber between the tubes 7 and8 to the cooled gas outlet 5, FIGURE 1, or 25, FIGURE 3. A water spray31 is mounted on a piece of pipe 32 welded to the coolant tube 10 in thebell section 11 thereof, and the spray nozzle 31 is connected to thewater supply line 17 which supplies water under pressure to produce avery fine spray, as shown in FIGURE 7, there being two nozzles shown oneach each of the tubes 10.

The fine spray of coolant, such as water, into the bellshaped end of thetubes 10 is drawn through the tubes by the exhaust fan 28 and the airsaturated with the coolant is exhausted into the chamber 27. The annulusbetween the fluid tube 10 and the shroud tube 8 is sized so that ameasurable pressure drop occurs in the air-coolant mixture flowingthrough the annular space between the tube.

This pressure drop plus any rise in temperature of the air coolant mixin the annulus evaporates the coolant and the latent heat ofvaporization contributes largely to the cooling of the tube throughwhich the hot gases flow. The air at the exaust end of the tube is lowerin pressure and is saturated to about relative humidity or more if 15inches of water negative pressure occurs at the exhaust end with 350s.c.f.m. of air exhausted. The volume of the spray nozzle will be aboutpounds of coolant per hour with the air entering at 85 F. at a relativehumidity of 70% if the coolant is water. The 100 pounds of water of thespray nozzle is evaporated in the annulus. If the outer tube isinsulated, the latent heat evaporation would have to come from the gasesin the inner tube. This cooling eflect, together with the convectioncooling of the air cooling mixture traveling rapidly in the annulusbetween the water tube and shroud tube causes very rapid cooling of thegases in the inner tube.

An advantage of this type of fluid cooling is that if the gases in theinner tube are under positive pressure, the coolant cannot contaminatethe gases being cooled in case of any leaks in the system.

The coil annealing apparatus with which "the cooling system is used, isshown in FIGURE 8 in which coils 35 of steel or other metal sheetmaterial are mounted on a hearth plate 36 on base 10 and are separatedby convector plates 37. The coils are mounted in a metal housing 38constituting an inner shell or cover surrounded by an insulating jacket39 in spaced relation therewith. Hot gases are supplied through a nozzle40 to the eye 41 of coils 35 from which they pass through convectorplates 37 to the space 42 between the coils 35 and housing 38, thencethrough radial passages 43 in hearth plate 36 to be recirculated throughinjector nozzle 44 and pass out through outlet 45. A burner 46 and pipelines 47 and 48 are utilized for purging the annealing chamber ofatmospheric gases such as air, which is no part of the presentinvention.

It is evident from the foregoing description of this invention thatspray and negative pressure cooling systems described therein provide asimple and efiicient means for cooling hot gases in industrial heatingsystems such as annealing apparatus and the like, or in heat exchangers.

Although one embodiment of the invention has been herein illustrated anddescribed, it will be evident to those skilled in the art that variousmodifications may be made in the details of construction withoutdeparting from the principles herein set forth.

We claim:

1. Cooling system for coil annealing apparatus in which hot-gaseswithdrawn from thecoil-annealing 'charhber are delivered to a header boxhaving flow tubes open at both ends, extending therefrom the flow tubesbeing contained Within outer tubes closed at one end against which thegases impinge to be diverted and caused to How in the reverse directionthrough the space between said tubes to a second header boxhaving a flowpassage back to the coil annealing chamber, and coolant tubessurrounding said outer tubes and extending substantially the full lengthof said tubes having a bell-shaped portion at the end adjacent said lastnamed header box and having the other end opening to an exhaustchamber,means for spraying a coolant into said bell shaped portion andmeans for maintaining negative pressure in said exhaust chamber to drawair from said bell-shaped portion through the space between said outertube and coolant tube to cause rapid cooling of the gases flowingthrough the firstnamed tubes.

References Cited UNITED STATES PATENTS ROBERT A. OLEARY, PrimaryExaminer.

T. W. STREULE, Assistant Examiner.

